Thread-cutting mechanism for sewing machines



July 28, 1931. E. B. ALLEN 1,316,308

THREAD CbTTING MECHANISM FOR SEWING MACHINES Filed Oct. 19, 1929 2 Sheets-Sheet l Edward biAZZen E. B. ALl,EN I THREAD CUTTING MECHANISM FOR SEWING MACHINES July 28, 1931.

Filed Oct. 19, 1929 2 Sheets-Sheet 2 gin wanker Edwardfl. Allen v (1mg Patented July 28, 1931 UNITED STATES JERSEY PATENT, OFFICE znnwnnnn. ALLEN, or nnw'r'own, ooimno'rronr, ASSIGNOR TO THE SINGER MANU FACTURING ooivirAnyyor ELIZABETH, NEW JERSEY, e CORPORATION OF NEW THREAD-CUTTING MECHANISM FOR SEWING MACHINES Application filed October 19, 1929. Serial No. 400,768.

This invention relates to thread-cutting mechanism for sewing machines, 'morepar-.

ticularly of the two-thread type, and has for an objectv to'provide simplified means for "fisevering the under-thread and holding the under-thread end for the formation of the initial stitches of the next sewing operation. A-

further object of the invention is to provide I means for severing and holding the underthread so that, in the finished product of the machine, the beginning and finishing ends of the under-thread of the stitched work will be of minimum length. Still further, the invention has for an object to provide an improved under-thread cutting and nipping mecha-' nism particularly adapted for use in sewing machines of the well known Singer 71- Class, represented in the U. S. Patent to Allen, No. 885,310, of Apr. 21, 1908.

To the attainment of the ends in, view, cooperating thread-cutting and -nipping blades are mounted in a fixed. operating location or thread-cutting position at the underside of the throat-plate of the'machine close tothe needle-hole but slightly'to one sidethereof.

Means are provided for bending or carrying the under-thread to one side sufliciently to bring it within range of the movable element.

or elements of the thread-cutter and -nipper for the thread-severing operation. Means are also provided for opening the thread-f cutter and -nipper momentarily, after the initial stitches of the next sewing operation have been formed, to release the beginning end of the under-thread. V Afeature of'the invention is the provision of means for open ing and subsequently closing the thread-cutter and -nipper in one continuous movement I -nipping mechanism, in its preferred embodiment, showing the thread-bender at threadcutting position. Fig. 2 is a similar View showing the thread-bender in retracted position. Fig.3 is a section on the line Fig. 1. Fig. 4 is'a section on the line 4-4," Fig. 1. Fig. 5 is a perspective view of the thread cutter and -nipper. Fig. 6 is a section on the line 6-6, Fig. 1. Fig. 7 is a perspective view of the under-thread catcher or bender. Fig. 8 is a section on the line -88', F ig, '1. Fig. 9 is a complete bottom plan view of the machine shown in Fig. 1, and Fig. 10 is a View showing certain of the threadcutter operating connections looking from the rear end toward the front end of the machine.

The machine is of the straight buttonhole sewing type and is constructed substantially in accordance .with my application, Serial No. 400,767, filed herewith, and the follow ing copending applications: E. B. Allen and 1928; and E. E. Allen, Serial No. 367,511, filed Flay 31, 1929. I

The machine comprises the usual flat bedl above which is the usual superstructure (not shown). The stitch-forming mechanism comprises the reciprocating and laterally jogging needle 2 and cooperating shuttle 3 which are driven as usual from the mainshaft 8, Fig. 9, the period of operation of which is controlled by the usual stop-motion device 4. The shuttle includes the usual thread-case 3 for the mass of under-thread t.

The machine has a work-clamp 5,'Fig. 9', which is mounted as usual on the longitudinal slide-plate 6 having movement lengthwise of the bed 1, in the cross slide-plate 7 which has movement transversely of the bed 1. Movements are imparted to the slide-plates 6 and 7 by the feed-wheel 8 having the longitudinal feed-cam 9 and lateral feed-cam 10 which move the work-clamp during the sewing operation to place the stitches in the desired order or arrangement. I

The needle works through a hole 11 in the throat-plate 12; the hole 11 being in the form of a slot to accommodatetheneedle in its" different positionsof descent due to its lateral jogging movment. In sewing the final barring. stitches of a straight buttonh-ole it is WV. Myers, Serial No. 272,416, filed Apr. 24, I

i at 25 and moves with the latter.

customary in a machine of the present type to increase the amplitude of vibration of the needle, so that the needle will descend alternately in the positions 2 and 2. In the present machine the follower nose 18 of the usual stop-motion tripping lever 14-. is adjusted so that it will be engaged by the tripping point 15 on the feed-wheel 8 at the proper time to stop the machine with the needle out of the work at its position 2, rather than at its alternate position 2, so that the last stitch in the work will be made closely as possible to the thread-cutter and -nipper to be described.

The thread-cutting and -nipping mecha nism comprises spaced stationary cutter and nipper blades, 16 and 1. respectively, between which are pivoted at 18 the movable cutter and nipper blades, 19 and 20, respectively. The cutter-blade 19 has extending laterally therefrom an actuating arm 21 formed with a downturned lip 22 a'll ording a striking face for engagement by the cuttero eratim push-bars 22% The movable nlpper-b ade is pinned to the cutter-blade The thread cutting and -nipping device, including the stationary blades, 16, 17 and movable blades, 19, 20, is mounted by screws 20" on the under side of the guide-rib element 7', Fig. 8, of the cross slide-plate 7 in a position close to the end of the needle-clearance slot 11 in the needle-throat member 12. The spring 26 connected to the arm 21 tends to move the blades 19, 20 to closed position between the station ary blades 16, 17 to cut and nip the bobbinthread.

As the thread-cutter is positioned and has a range of action slightly to one side of the needle-path, it will not of itself. catch the under-thread It. Means are therefore pro vided to carry the wider-thread into the range of action of the thread-cutter. For this purpose there is pivoted at 27 on the cross slide-plate 7 a thread-engaging arm or thread-bender 28 the free end of which is formed with a horizontal slot 29, Figs. 7 and 8, providing top and bottom legs 30, 31 strad-,

dling the movable blades 19, 20 while the latter are in open position, shown in Figs. 1 and 3. The legs 30, 31 are each formed in one edge with a thread-catching notch defining the thread-catching fingers 32, 38 which catch the bobbin-thread t and carry it between the open jaws of the thread-cutting and -nipping device, Figs. 1 and l; the top and bottom fingers holding the thread more nearly at right angles to the plane of action of the movable blades 19, 20, than it would be held by one finger alone.

The arm 28 is actuated by a link-connection 34 with a slide-bar 35 from which depends a stud 36 embraced by the forked end 37 of a lever 38 fulcrumed at 39 below the bed 1 and at its other forked end 40 embracing a ballstud 41 carried by the lower end of a lever 12 sustained by and free to turn relatively to the rock-shaft 43. The lever 12 carries a roller stud 44 which is engaged by the cam-shaped end 15 of an arm 46 fixed to the rod 47. When the rod 4.7 is projected downwardly by a pull on the lever 48, also loose on the shaft 43, the cam-end 45 of the arm 46 swings the lever 28 across the lead of the bobbin-thread from the position shown in Fig. 2 to that shown in Fig. 1; whereby the bobbin-thread is caught by the fingers 32, 33 and carried into the open jaws of the thread-cutter.

Slidably mounted on the underside of the cross slide-plate 7, between the guide-pins 4.9, 50, is the push-rod or latch 23 previously re ferred to which carries a stud-screw 51 pass ing through a slot 52 in the arm 28. The tail 53 of the latch is inclined to the left, F ig. 1, and is connected by a spring 5 1 to an arm 55 rigid with the cross slide-plate 7 The nose 56 of the latch 23 is inclined to the right and is adapted to engage the lip 22 of the threadcutter arm 21 in its dotted line position, Fig. 2, and open the threadcutter to its full line position, Fig. 1, (which has reached nearly its fully open position) during the thread-bending movement of the thread-catching arm 28. During the slight further and final movement of the arm 28, the inclined tail 58 of the latch 23 engages the guide-pin 4-9 and is deflected to the right, Fig. 1, thus swinging the latch about theguidc-pin 50 as a fulcrum. and disengaging its nose 56 from the lip 22, whereupon the spring 26 quickly swings the mov able blades 19, 20 to closed or dotted line position, Fig. 1.

At the beginning of the neat sewing Opera'- tion and after the initial stitches have been formed, the nipped bobbin-thread t, Fig. 6, is released by movement of the push bar 24: from the dotted line position shown in Fig. 2 to full line position, during which movement the push-bar 24 engages the lip 22 of the thread cutter arm 21 and opens the nipper-blades. The push-bar 24 is formed at one end of the slide-bar 57 from which depends a stud 58 entering the slot 59 in one end of a lever 60 fulcrumed at 61 below the bed 1 and carrying an adjustable cam-follower nose 52 which is engaged by the nipper-opening cam 53 on the feed-wheel 8. The levers 60 and 38 have connected thereto the respective recovery springs 62 and 63.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a two-thread sewing machine, the combination with a throat-plate having a needle-hole, of a thread-cutter and -nippcr mounted below the throat-plate in threadcutting and nipping position spaced laterally of the needle-hole, and means for carrying the under-thread laterally to the threadcutter and -nipper.

2. In a sewing machine, uppenthread mechanism, under-thread mechanism, a fiat bed, a throat-plate having a needle-hole, a thread-cutter and -nipper mounted below the throat-plate and including an element movable in a plane parallel to the plane of the sewing machine bed with a range of action at one side of and excluding the space directly below the needle-hole, and means for carrying the under-thread laterally into the range of movement of the thread-bender in carrying action of the movable element of the threadcutter and -nipper.

3. The combination with .a thread-cutter having a member movable between open and closed positions, a spring for moving said member to closed position, a thread-bender movable from retracted to thread-cutting position for carrying the thread to be cut into the range of action of said movable member, and means connected to said thread-bender for opening and releasing said movable member in one continuous movement of the threadbender from retracted to thread-cutting position. e

4. In a two-thread sewing machine, the combination witha throat-plate having a needle-hole, of a thread-cutter and -nipper mounted below the throat-plate at one side of the needle-hole, a spring for closing the thread-cutter and -nipper, an under-thread bender, and means connected to the underthread bender for opening and releasing the thread-cutter and -nipper in one continuous the under-thread laterally to the threadcutter and -nipper. r

5. In a tWo-thread sewing machine, the combination of a throat-plate having a needle-hole, of a thread-cutter and -nipper mounted below said throat-plate at one side of the needle-hole and including a movable member, and a thread-bender arm having a hooked free end which is slotted to straddle the movable member of said thread cutter and -nipper.

6. In a two-thread sewing machine, a needle, a throat-plate having a needle-hole, a spring-actuated thread-cutter elementmounted below said throat-plateand having a range of action atone side of and in nonintersecting relation with the needle-path, an under-thread catcher movable laterally of the needle-path for carrying the underthread into the range of action of the threadcutter, and means for setting and releasing the thread-cutter during the thread-carrying movement of the thread-catcher.

In a two-thread sewing machine, the combination with a throat-plate having a needle-hole, of thread'cutting and -nipping means including relatively movable members mounted at the underside of the throat-plate with a range of action slightly to one side of the needle-hole, and means for engaging the under-thread and carrying it laterally to a position within the range of action of said relatively movable members.

8. The combination with a throat-plate having a needle-hole, of a thread-cutter and -nipper having cooperating fixed and movable jaws disposed below the throat-plate at one side of the needle-hole, an under-threadbender, means actuated by said under-thread bender for opening said movable .jaw, a

means movable across the lead of the underthread and toward said thread-cutting and -nipping means to carry the under-thread laterally to thread-cutting and -nipping p0 sition, and actuating means ,for imparting an opening movement to the 'movable element of the thread-cutting and -nipping means during the approach of the under-thread to thread-cutting and -nipping position, said actuating means releasing said movable element upon the arrival of the under-thread at thread-cutting and -nipping position.

10. The combination with a flat sewing machine bed, of a thread-cutterand ,thread- 11. In sewing machine thread-cutting mechanism, a spring-actuated thread-cutter, a thread-bender, and a latch actuated by, said thread-bender for setting and releasing the thread-cutter in one continuous movementof said thread-bender. 7

12.Thread-cutting mechanism for sewing machines comprising, actuated thread-cutting element, a movable thread-bender element adapted to carry the thread to be cut to a position within the? range of action of the thread-cutting ele-. ment, means for actuating the thread-bender element, a latchactuated by the threada movable springbender element and adapted to engage and set the thread-cutter element, said latch having a cam-portion, and stationary means engaged by said cam-portion for disengaging said latch from said thread-cutting element to release the latter.

In testimony whereof, I have signed my name to this specification.

EDWARD B. ALLEN. 

